The Thorny Problem of Keeping the Internet's Time

An obscure software system synchronizes the network's clocks. Who will keep it running? From a report: To solve the problem of time synchronization on the arpanet, computer scientist David Mills built what programmers call a protocol -- a collection of rules and procedures that creates a lingua franca for disparate devices. The arpanet was experimental and capricious: electronics failed regularly, and technological misbehavior was common. His protocol sought to detect and correct for those misdeeds, creating a consensus about the time through an ingenious system of suspicion. Mills prided himself on puckish nomenclature, and so his clock-synchronizing system distinguished reliable 'truechimers' from misleading 'falsetickers.' An operating system named Fuzzball, which he designed, facilitated the early work. Mills called his creation the Network Time Protocol, and N.T.P. soon became a key component of the nascent Internet. Programmers followed its instructions when they wrote timekeeping code for their computers. By 1988, Mills had refined N.T.P. to the point where it could synchronize the clocks of connected computers that had been telling vastly differing times to within tens of milliseconds -- a fraction of a blink of an eye. 'I always thought that was sort of black magic,' Vint Cerf, a pioneer of Internet infrastructure, told me.

Today, we take global time synchronization for granted. It is critical to the Internet, and therefore to civilization. Vital systems -- power grids, financial markets, telecommunications networks -- rely on it to keep records and sort cause from effect. N.T.P. works in partnership with satellite systems, such as the Global Positioning System (G.P.S.), and other technologies to synchronize time on our many online devices. The time kept by precise and closely aligned atomic clocks, for instance, can be broadcast via G.P.S. to numerous receivers, including those in cell towers; those receivers can be attached to N.T.P. servers that then distribute the time across devices linked together by the Internet, almost all of which run N.T.P. (Atomic clocks can also directly feed the time to N.T.P. servers.) The protocol operates on billions of devices, coÃrdinating the time on every continent. Society has never been more synchronized.

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